Pro-Russians storm Ukrainian navy base in Crimea

Crimean pro-Russian self-defense forces open a gate to the territory of the Ukrainian navy headquarters in Sevastopol, Crimea, Wednesday, March 19, 2014. (AP Photo/Andrew Lubimov)

CNN — Ukraine’s acting president gave Crimea’s separatist leaders a deadline to release hostages Wednesday after pro-Russian activists stormed the former Soviet state’s navy headquarters in the region.

Amid signs the uneasy standoff between pro-Russian and Ukrainian forces could ignite into bloody conflict — a day after Moscow claimed Crimea as its own — almost 300 armed pro-Russian supporters took over the naval base in Sevastopol, said Marina Kanalyuk, assistant to the commander of Ukraine’s navy fleet.

“They are everywhere here, they surround us, they threaten us,” she said, adding that she was sure that Russian security forces were involved.